Two strains of an unknown Gram-positive, catalase-negative, facultatively anaerobic coccus originating from the reproductive tract of horses were characterized by phenotypic and molecular taxonomic methods. Comparative 16S rRNA gene sequencing studies demonstrated that the two strains constitute a new subline within the lactic-acid group of bacteria, close to, but distinct from, Abiotrophia defectiva, Globicatella sanguinis and close relatives. The unknown bacterium was readily distinguished from other described Gram-positive, catalase-negative cocci by biochemical tests and electrophoretic analysis of whole-cell proteins. On the basis of phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Eremococcus coleocola gen. nov., sp. nov. The type strain of Eremococcus coleocola is CCUG 38207T.